title: Genetic drift of influenza A(H3N2) viruses during two consecutive seasons in 2011-2013 in Corsica, France.
abstract: The 2011-2012 and 2012-2013 post-pandemic influenza outbreaks were characterized by variability in the A(H3N2) influenza viruses, resulting in low to moderate vaccine effectiveness (VE). The aim of this study was to investigate the molecular evolution and vaccine strain match of the A(H3N2) influenza viruses, having been circulated throughout the population of the French Corsica Island in 2011-2012 and again in 2012-2013. Clinical samples from 31 patients with confirmed A(H3N2) influenza viruses were collected by general practitioners (GPs) over these two consecutive seasons. An analysis of genetic distance and antigenic drift was conducted. Based on a hemagglutinin (HA) aminoacid sequence analysis, the Corsican A(H3N2) viruses fell into the A/Victoria/208/2009 genetic clade, group 3. All influenza viruses were characterized by at least four fixed amino acid mutations which were: N145S (epitope A); Q156H and V186G (epitope B) Y219S (epitope D), with respect to the A/Perth/16/2009 (reference vaccine strain for the 2011-2012) and the A/Victoria/361/2011 (reference vaccine strain for the 2012-2013). Using the p(epitope) model, the percentages of the perfect match VE estimated against circulated strains declined within and between seasons, with estimations of <50%. Overall, these results seem to indicate an antigenic drift of the A(H3N2) influenza viruses which were circulated in Corsica. These findings highlight the importance of the continuous and careful surveillance of genetic changes in the HA domain during seasonal influenza epidemics, in order to provide information on newly emerging genetic variants.
authors.affiliation: INSERM, U707, Paris, France; Laboratory of Virology, EA 7310, University of Corsica, Corte, France.
authors.forename: Anais
authors.initials: A
authors.lastname: Fantoni
authors.forename: Christophe
authors.initials: C
authors.lastname: Arena
authors.forename: Laura
authors.initials: L
authors.lastname: Corrias
authors.forename: Nicolas
authors.initials: N
authors.lastname: Salez
authors.forename: Xavier Nicolas
authors.initials: XN
authors.lastname: de Lamballerie
authors.forename: Jean Pierre
authors.initials: JP
authors.lastname: Amoros
authors.forename: Thierry
authors.initials: T
authors.lastname: Blanchon
authors.forename: Laurent
authors.initials: L
authors.lastname: Varesi
authors.forename: Alessandra
authors.initials: A
authors.lastname: Falchi
mesh_terms: D000293:Adolescent; D000328:Adult; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D000940:Antigenic Variation / Q000235:genetics*; D001483:Base Sequence; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D005260:Female; D005602:France / Q000453:epidemiology; D040961:Genetic Drift; D006389:Hemagglutinins, Viral / Q000235:genetics*; D006801:Humans; D053122:Influenza A Virus, H3N2 Subtype / Q000235:genetics*; D007252:Influenza Vaccines; D007251:Influenza, Human / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D012621:Seasons; D017422:Sequence Analysis, DNA; D055815:Young Adult
chemical_list: D006389:Hemagglutinins, Viral; D007252:Influenza Vaccines
keywords: hemagglutinin; vaccine effectiveness; vaccine strain; virological surveillance